This application proposes five inter-related studies of Auditory Mechanisms at the chemical-molecular, genetic, and neural levels. Project I plans to study chemical-molecular mechanisms which affect afferent and efferent responses as well as distortion product emissions in the ear. Otoacoustic emissions and the development of their susceptibility to contralateral stimulation are the targets for Project III, along with selected clinical and genetic studies. Genetic studies are the focus of Project II and parts of Project IV, which also proposes to study the Trophic effects of GM-1 Gangliosides on genetically and artificially deafened mice. Project V plans to study the trophic effects in deaf animals of GM-1 gangliosides when combined with electrical stimulation using cochlear implants.